Chemical composition alteration of tobacco



United States Patent 3,351,066 CHEMICAL COMPOSITION ALTERATION OF TOBACCO Harry R. Colgate, 4868 Browndeer Lane, Palos Verdes, Calif. 92266 No Drawing. Filed July 20, 1965, Ser. No. 473,500 6 Claims. (Cl. 131140) This invention relates in general to tobacco improvement, and in particular to an improved process for altering the chemical composition of tobacco for the purpose of rendering the tobacco smoke less harmful to inhale.

This invention differs from the teachings of prior patents that utilize the principles of steam distillation carried out at low temperature in a partial vacuum. The principle that this invention employs is a relationship between certain harmful constituents in tobacco that create health hazards in tobacco smoke, and the means for removing those constituents without rendering the tobacco useless for its intended purpose.

This invention disclosure describes a process for altering the chemical composition of cigarette or cigar tabacco so as to reduce the concentration or remove entirely those elements that may become toxic constituents of the smoke. The compounds that may be removed, or whose concentration can be materially reduced, are those whose boiling point temperature at atmospheric pressure is close to, or lower than, the combustion temperature of tobacco when smoked in cigarette form (approximately 625 F). This process also reduces the combustion temperature of the tobacco, thereby altering the rate at which oxidation products may be formed. This will reduce the concentration of these compounds in the smoke.

Tobacco constituents that may be removed or their concentration reduced by the techniques of this invention are oil and tar fractions, polycylic hydrocarbons that are typically, but not limited to benzo(a)pyrene, dibenz(a,h) anthracene, benzo(b)fiuoranthene, benzo(i)fiuoranthene, benz(a)anthracene, chrysene, benzo(e)pyrene, benzo (g,h,i)perylene and benzo(k) fluoranthene. Phenols, wax fractions, acid fractions, and the alkaloids are among the other principal constituents that can be extracted from tobacco. The processed tobacco will have good smoking properties when used to manufacture cigarettes and cigars.

Nicotine has been partially removed from tobacco by other methods. These variously include soaking with alkali solutions of several types, hot water, steam, ethyl ether, etc. Water, steam, and low heat have been used in combination with vacuum. This latter process will carry off the free nicotine found in tobacco, but will not carry off more than a small quantity of nicotinic acid. The former processes have to be very carefully handled to prevent traces of the chemicals used remaining in the tobacco which will produce an unpleasant taste in the tobacco smoke and may also produce mild undesirable biological effects.

An actual batch process which produces commercial grade tobacco products will further illustrate the invention and its techniques. The tobacco produced by this process has been tested by an independent laboratory Without knowledge of the invention, or the manner in carrying out the process, and the results reported herein have been gleaned from such independent testing laboratory.

A wire mesh basket is employed to hold the tobacco being treated. There are no critical limits on the size or shape of such basket, but for efficiency of process, it is desirable that the depth of the tobacco from any surface be minimized in order to allow uniform rapid heating and thus produce an economical system.

i A thermocouple is preferably buried into the middle of the tobacco being processed in order to deter-mine the penetration of heat to the desired degree. This thermocouple is preferably calibrated to 600 F.

An electrical heating coil is placed in close proximity to the outer surface of the mesh basket without actually touching, in order that the tobacco may be quickly and uniformly heated during the treating process. This placement will keep the temperature of the heating coil at minimum for attaining correct process temperature for the tobacco farthest from the heating coil.

This basket with heating coil is then placed in a vacuum vessel capable of withstanding low pressures in the range of up to 1 10- mm. of Hg.

This invention employs very high vacuum in order to enable the correct application of high temperature without altering the physical appearance and smoking char acteristic of the resultant product. The high vacuum system has a charcoal trap, an oil seal mechanical pump, and an oil diffusion high vacuum pump. The mechanical pump alone will produce a vacuum of 3 to 50 microns. The oil diffusion pump in combination with the mechanical pump will produce a vacuum of 1X 10* mm. of Hg.

In order to assure maximum success of resultant product, it is desirable that the internal parts of the process vessel be degreased and thoroughly dried, and the basket lightly vacuum fired before processing tobacco. These measures reduce tobacco oxidation during processing. It is part of the success of the present invention that the oxidation of tobacco be prevented.

With the basket lightly packed with the tobacco to be treated, and the basket placed in the vacuum chamber with the thermocouple placed in the tobacco, the mechanical pump is turned on and the power supply and thenmocouple'bridge are connected to the heating coil and the thermocouple. When the pressure inside the process vessel has been reduced to approximately 10 microns by the mechanical pump, the oil diffusion pump is cut into the system and the pressure then is controllable in a range of 10 microns to 1.O 10 mm. Hg. When the selected pressure has been reached, the heating coil is activated. By varying the input to the coil from the power supply, the desired process temperature may be obtained.

With this physical set-up, excellent-quality smoking tobacco has been produced which has substantially no elements capable of producing lung irritation remaining. The independent testing shows of all forms of nicotine and of total alkaloids removed. This invention is not limited to a complete extraction of all elements, but is selective and may be controlled to produce any desired properties.

Non-selective extraction of most elements that boil out of tobacco during the combustion process of smoking can be carried out at 350 F. in a controlled high-vacuum environment of 5X10- mm. Hg. The process tobacco will retain good smoking properties. The completeness of the extraction will be determined by the length of time tobacco under process is held at these process conditions. Lower pressure and slightly higher temperatures will improve the extractive yield, but are difiicult to con trol to prevent the excessive oxidation of the product. Therefore, process temperatures are limited by the degree of oxidation which produce smoking quality standards by taste preferences.

It has been found that those elements that have a boiling point above 625 F. at atmosphere can be reduced by this process, but not completely eliminated.

Selective extraction can be accomplished in sequentially ascending order of boiling points at any specific pres sure. Selection is limited only by the boiling point characteristics of the constituent(s) selected for extraction in the useful pressure ranges that prevent oxidation during processing. Extraction of a few low boilers, such as phenol, can take place at a pressure temperature combination of 100 F. and 500 microns, but undesirable oxidation of the tobacco will take place. Oxidation is prevented by keeping pressures for desired extractions in the range 1.0 10 to 1.0 10 mm. of Hg. For most of the undesirable constituents like nicotine and nicotinic acid, fluoranthene, benzo pyrene, dibenzanthracene process ternperature/ pressure combinations of 225 F. and 4.0 10- mm. of Hg will work well and produce a processed tobacco that has little oxidation. For the higher boiling oils, wax fractions and such polycylics as the pyrenes and the anthracenes, process temperatures of 300 F. and pressures of 5.0 10 are required. Once temperature equilibrium is reached, process times for the controlled pressure temperature phase vary from a few minutes to one hour. The process time limiting factors are size of the tobacco charge being processed and the speed of the high-vacuum pumps. It is desirable to use the lowest pressure readily obtainable in the processing pressure range to both speed up processing and lower the required processing pressures.

Processing carried out at 300 F. and 5.0 10 mm. of Hg for ten minutes removes 75% of the total nicotine and 80% of the total alkaloids. During processing under these conditions, :a yellow-orange and brownish oil-like tar will also be deposited on the Walls of the process vessel. These constituents are, in part, higher boiling oils, tar fractions, pyrenes and anthracenes which require more severe process conditions for high percentage removal.

In general, when the process is used for treating smoking tobacco to remove controlled quantities of total oil, tar, and wax fractions thereof, the heat range may vary between 200 to 350 F.

Whenever the process is used to remove the total quantities of benzo(-a)pyrene, dibenz(a,h)anthracene, benzo(b)fluoranthene, benzo(j)fluoranthene and benz (a)anthracene, a temperature range is workable within the range of 150 to 350 F.

When the interest is in removing controlled quantities of total phenols, a heat range is applicable within 100 to 200 F. However, the total alkaloids are treated to remove controlled quantities thereof by heating Within a temperature range of 200 to 350 F.

Finally, to remove controlled quantities of total nicotine, both bound and free, a temperature range is applicable between 150 to 300 F.

When the temperature/ pressure process phase has been completed, the heating coil is cooled while the tobacco being processed remains under vacuum. Temperature is monitored until it is below 125 F. The vacuum may then be broken. Undesirable oxidation will take place if the processed tobacco has not been cooled in the vacuum environment until the low temperature is reached.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention which is, therefore, not to be limited to the details disclosed herein, but is to be afforded the full scope of the invention as hereinafter claimed.

What is claimed is: I

1. The process of treating smoking tobacco to remove undesirable fractions thereof, comprising the following steps:

subjecting the tobacco to reduced pressure in a vacuum chamber within a range of 500 microns down to 1 X 10- mm. Hg;

:after the pressure on the tobacco has been reduced to at least 500 microns, applying heat to bring the tobacco to a desired temperature range;

maintaining the heat and reduced pressure for a period of time within a range of 15 minutes to 1 hour;

after the lapse of time necessary within said range, allowing the tobacco to cool while being held at said reduced pressure until the tobacco is not over 125 F.; and

4;- returning the pressure to atmospheric and removing the treated tobacco.

2. The process of treating smoking tobacco to remove controlled quantities of total oil, tar and wax fractions thereof, comprising the following steps:

subjecting the tobacco to reduced pressure in a vacuum chamber within a range of 500 microns down to l 10 mm. Hg;

after the pressure on the tobacco has been reduced to at least 500 microns, applying heat to bring the tobacco to a temperature range 200 F. to 350 F.;

maintaining the heat and reduced pressure for a period of time within a range of 10 minutes to one hour during which time the desired quantity of total alkaloids will have been removed;

after the lapse of time necessary within said range, allowing the tobacco to cool while being held at said reduced pressure until the tobacco is not over 125 F.; and

quickly returning the pressure to atmospheric and removing the treated tobacco.

3. The process of treating smoking tobacco to remove controlled quantities of benzo(a)pyrene, dibenz(a,h)

anthracene, benzo( b)fluoranthene, benzo(j)fluoranthene and benz(a)anthracene, thereof, comprising the following steps:

subjecting the tobacco to reduced pressure in a vacuum chamber within a range of 500 micron-s down to 1x 10' mm. of Hg;

after the pressure on the tobacco has been reduced to at least 500 microns, applying heat to bring the tobacco to a temperature within the range of 150 to 350 F maintaining the heat and low pressure for a period of time within a range of 10 minutes to one hour during which time the desired quantity of total alkaloids will have been removed;

after the lapse of time necessary within said range,

allowing the tobacco to cool while being held at said izeduced pressure until the tobacco is not over 125 and returning the pressure to atmospheric and removing the treated tobacco.

4. The process of treating smoking tobacco to remove controlled quantities of total phenols thereof, comprising the following steps:

subjecting the tobacco to reduced pressure in a vacuum chamber within a range of 500 microns down to 1 10- mm. of Hg; after the pressure on the tobacco has been reduced to :at least 500 microns, applying heat to bring the tobacco to a temperature range within 100 F. to 200 F.;

maintaining the heat and low pressure for a period of time within a range of 10 minutes to one hour during which time the desired quantity of total alkaloids will have been removed;

after the lapse of time necessary within said range,

allowing the tobacco to cool While being held at said reduced pressure until the tobacco is not over 125 F.; and

returning the pressure quickly to atmospheric and removing the treated tobacco.

5. The process of treating smoking tobacco to remove controlled quantities of total alkaloids thereof, comprising the following steps:

subjecting the tobacco to reduced pressure in a vacuum chamber within a range of 500 microns down 70 to 1 10' mm. of Hg;

after the pressure on the tobacco has been reduced to at least 500 microns, applying heat to bring the tobacco to a temperature range 200 to 350 F.; maintaining the heat and low pressure for a period of time within a range of 10 minutes to one hour during which time the desired quantity of total alkaloids will have been removed;

after the lapse of time necessary within said range,

allowing the tobacco to cool while being held at said reduced pressure until the tobacco is not over 125 F and returning the pressure quickly to atmospheric and removing the treated tobacco.

6. The process :of treating smoking tobacco to remove controlled quantities of total nicotine, both bound and free thereof, comprising the following steps;

subjecting the tobacco to reduced pressure in a vacuum chamber within a range of 500 microns down to 1x10 mm. of Hg; after the pressure on the tobacco has been reduced to at least 500 microns, applying heat to bring the tobacco to a temperature range 150 to 300 F.;

maintaining the heat and low pressure for a period of time Within a range of 10 minutes to one hour during which time the desired quantity of total alkaloids will have been removed;

References Cited UNITED STATES PATENTS 8/1911 Sartig 131-143 3/1934 Smith 131-140 7/1937 Smith 131-142 X 7/1940 Palmer 131-140 10/1940 Palmer 131-440 10/ 1940 McCorkhill 131140 FOREIGN PATENTS 7/ 1915 Great Britain. 5/ 1940 Great Britain.

ALDRICH F. MEDBERY, Primary Examiner. 

1. THE PROCESS OF TREATING SMOKING TOBACCO TO REMOVE UNDESIRABLE FRACTIONS THEREOF, COMPRISING THE FOLLOWING STEPS: SUBJECTING THE TOBACCO TO REDUCED PRESSURE IN A VACUUM CHAMBER WITHIN A RANGE OF 500 MICRONS DOWN TO 1X10**7MM. HG; AFTER THE PRESSURE ON THE TOBACC O HAS BEEN REDUCED TO AT LEAST 500 MICRONS, APPLYING HEAT TO BRING THE TOBACCO TO A DESIRED TEMPERATURE RANGE; MAINTAINING THE HEAT AND REDUCED PRESSURE FOR A PERIOD OF TIME WITHIN A RANGE OF 15 MINUTES TO 1 HOUR; AFTER THE LAPSE OF TIME NECESSARY WITHIN SAID RANGE, ALLOWING THE TOBACCO TO COOL WHILE BEING HELD AT SAID REDUCED PRESSURE UNTIL THE TOBACCO IS NOT OVER 125*F.; AND RETURNING THE PRESSURE TO ATMOSPHERIC AND REMOVING THE TREATED TOBACCO. 